Isomerization Of Glucose Research Articles

Unlocking the Anion Effect on Steerable Production of 5‐Hydroxymethylfurfural

AbstractHomogeneous metal salt catalysts play a pivotal role in industrial production of 5‐hydroxymethylfurfural (HMF). Herein, we first proposed the anion effect on steerable production of HMF using metal salts with different anions as catalyst in a biphasic system of tetrahydrofuran (THF)/NaCl aqueous solution (NaCl aq). Notably, the anions affected the catalytic activity of the metal salts, leading to an order of magnitude difference in the HMF yields, i.e., AlBr3 (74.0 mol %)>AlCl3 (60.8 mol %)>Al2(SO4)3 (35.2 mol %)>Al(NO3)3 (14.9 mol %). The anion effect on steerable production of HMF could be attributed to the proximity effect and electron tension. Anions form close‐range interactions with glucose molecules by proximity effect to promote electron transfer, facilitating the isomerization of glucose to fructose. Besides, anions induce a reduction of the electron cloud density of glucose carbon atoms, generating electron tension that rapidly transforms glucose from the ground state to the transition state, thereby increasing the HMF yield. Based on the revelation of anions effect and evaluation of techno‐economic process, we expect to provides theoretical guidance for high‐throughput screening of metal salt catalysts in industrial biorefinery.

Unlocking the Anion Effect on Steerable Production of 5-Hydroxymethylfurfural.

Homogeneous metal salt catalysts play a pivotal role in industrial production of 5-hydroxymethylfurfural (HMF). Herein, we first proposed the anion effect on steerable production of HMF using metal salts with different anions as catalyst in a biphasic system of tetrahydrofuran (THF)/NaCl aqueous solution (NaCl aq). Notably, the anions affected the catalytic activity of the metal salts, leading to an order of magnitude difference in the HMF yields, i.e., AlBr3 (74.0 mol %)>AlCl3 (60.8 mol %)>Al2(SO4)3 (35.2 mol %)>Al(NO3)3 (14.9 mol %). The anion effect on steerable production of HMF could be attributed to the proximity effect and electron tension. Anions form close-range interactions with glucose molecules by proximity effect to promote electron transfer, facilitating the isomerization of glucose to fructose. Besides, anions induce a reduction of the electron cloud density of glucose carbon atoms, generating electron tension that rapidly transforms glucose from the ground state to the transition state, thereby increasing the HMF yield. Based on the revelation of anions effect and evaluation of techno-economic process, we expect to provides theoretical guidance for high-throughput screening of metal salt catalysts in industrial biorefinery.

Density Functional Theory Study on Na+ and K+ Catalysis in the Transformation of Glucose to Fructose and HMF in Hydrothermal Environments

Hydrothermal carbonization (HTC) is an efficient method for converting biomass into biochar. Hydrochar contains catalytic components such as alkali and alkaline earth metals (AAEMs); however, the mechanisms by which highly active metals such as potassium (K) and sodium (Na) catalyze the conversion of small carbon–water compounds into hydrochar in hydrothermal environments remain unclear. In this study, glucose was used as a small molecule model, and Na+ and K+ were used as catalysts to investigate the catalytic reaction mechanism during the hydrothermal process using density functional theory (DFT). In the presence of different ions at various binding sites, glucose isomerizes into fructose, which subsequently undergoes three consecutive dehydration reactions to form 5-hydroxymethylfurfural (HMF). The results indicate that the catalytic effectiveness of Na+ and K+ in the isomerization of glucose to fructose is optimal when interacting with specific oxygen sites on glucose. For Na+, the interaction with the O1 and O2 oxygens provides the lowest reaction barrier of 37.16 kcal/mol. For K+, the most effective interactions are with the O3 and O4 oxygens and the O5 and O6 oxygens, resulting in reduced reaction barriers of 54.35 and 31.50 kcal/mol, respectively. Dehydration of fructose to HMF catalyzed by Na+ ions, the catalytic effectiveness at different positions is ranked as O5O6 > O1O5, whereas for K+, the ranking is O1O5 > O5O6. This study explores the catalytic effects of Na+ and K+ at different binding sites on the hydrothermal reactions of glucose at the atomic level, offering theoretical support for designing catalysts for the HTC of sludge.

Lactose hydrolysis in sheep and cow milk with varying fat levels to evaluate enzymatic production of lactulose

AbstractThis study aimed to perform lactose hydrolysis using free and immobilised β-galactosidase in cow and sheep milk with different fat levels, followed by lactulose synthesis through the isomerisation of glucose to fructose using immobilised glucose isomerase. There was no significant difference (P > 0.05) in lactose hydrolysis (>95%) using the free enzyme in the different types of milk. In contrast, significant differences were observed for the hydrolysis of whole cow milk (WCM) and skimmed cow milk (SCM) with the immobilised enzyme (IE). WCM required a longer hydrolysis time (43 h). Thus, the fat content may have affected the lactose hydrolysis of bovine milk with immobilised β-galactosidase. No difference was observed for whole sheep milk and skimmed sheep milk hydrolysed by IE, possibly due to the presence of smaller fat globules, which did not affect the lactose hydrolysis. No significant differences were observed for lactulose synthesis in whole milk from the different species evaluated. The lactulose synthesis in cow and sheep milk by the enzymatic route may be a promising alternative, though further studies are required to optimise the production of this prebiotic in situ.

Phase effects in zirconia catalysed glucose conversion to 5-hydroxy methylfurfural.

5-(hydroxymethyl)furfural (HMF) is a key biomass derived platform chemicals used to produce fuel precursors or additives and value-added chemicals,synthesised by the cascade isomerisation of glucose and subsequent dehydration of reactively formed fructose to HMF over Lewis and Bronsted acid catalysts respectively. Zirconia is a promising catalyst for such reactions; however, the impact of acid properties of different zirconia phases is poorly understood. In this work, we unravel the role of the zirconia crystalline phase in glucose isomerisation and fructose dehydration to HMF. The Lewis acidic monoclinic phase of zirconia is revealed to preferentially facilitate glucose isomerisation, while the nanoparticulate tetragonal phase possesses Brønsted acid sites which favour fructose dehydration. Synergy between both zirconia phases facilitates cascade HMF production, with both catalysts investigated as physical mixtures in batch and flow reactor configurations. Usinga physical mixture of only 15 wt% m-ZrO2 with 85 wt% t-ZrO2 in either batch or packed bed reactor configuration is sufficient to reach equilibrium conversion of glucose for subsequent dehydration by the t-ZrO2 component. Under continuous flow, a six-fold increase in HMF production was obtained when operating with a physical mixture of m- and t-ZrO2 compared to that from a single bed of t-ZrO2.

One-Pot Conversion of Biomass Saccharides to γ-Valerolactone over a Versatile Tin-Containing Material.

The synthesis of biofuel γ-valerolactone (GVL) from accessible biomass is an attractive and challenging goal. Here, we report an efficient, one-pot, and mild strategy for the efficient production of GVL from various biomass saccharides without using any homogeneous acid as a co-catalyst and molecular hydrogen as a hydrogen donor. A versatile porous tin-containing material (Sn(M)-S) was designed as an individual heterogeneous catalyst. As high as 68.4% yield of GVL form glucose was achieved in the presence of ammonia borane as a solid hydrogen donor under mild conditions, with GVL yields of 76.2%, 68.9%, 62.5%, and 52.2% being obtained from fructose, sucrose, cellobiose, and cellulose, respectively. The synergistic effect of Sn and sulfonic acid group in Sn(M)-S not only provides appropriate Lewis acid sites to promote the isomerization of glucose into fructose but also affords abundant Brønsted sites for the following conversion steps. Moreover, Sn(M)-S(1) showed good stability and reusability during consecutive recycles.

Flow Semi-continuous Mechanochemistry as a Versatile and Efficient Tool for the Synthesis of Hydrocalumite and the Isomerization of Glucose to Fructose

Flow Semi-continuous Mechanochemistry as a Versatile and Efficient Tool for the Synthesis of Hydrocalumite and the Isomerization of Glucose to Fructose

Roles of Brønsted-Base and Brønsted-Acid Catalysts for Glucose Isomerization into Fructose and Fructose Dehydration into 5-Hydroxymethylfurfural

Roles of Brønsted-Base and Brønsted-Acid Catalysts for Glucose Isomerization into Fructose and Fructose Dehydration into 5-Hydroxymethylfurfural

Ultra-Dilute SnCl4-Catalyzed Conversion of Concentrated Glucose to 5-Hydroxymethylfurfural in Aqueous Deep Eutectic Solvent.

5-Hydroxymethylfurfural(HMF) is a versatile chemical synthesized from glucose dehydration catalyzed by metal chloride (MClx) in deep eutectic solvents (DESs). However, the low glucose concentration and high catalyst dosage hinder large-scale HMF production. Herein, we report an aqueous DES of tetraethylammonium bromide(TEAB)-glucose for converting concentrated glucose (40 wt%, relative to TEAB) using ultra-dilute SnCl4 (0.25 mol%), achieving a 62% yield of HMF. Ultra-dilute MClx-catalyzed selective conversion of glucose is feasible only when combining SnCl4 with Br-based DES, which is elucidated by density functional theory and molecular dynamic calculations. Using SnCl4 is essential due to its higher glucose isomerization activity than AlCl3 and CrCl3, which can be attributed to its low-barrier coordination with glucose and its barrier-free separation from fructose. Halide anions in DESs strongly interact with glucose, hindering the MClx-glucose coordination and thereby reducing MClx's activity for glucose isomerization. Consequently, Br-based DESs facilitate higher activity of MClx than Cl-based DESs, due to the weaker interaction between halide anion and glucose. In addition, we elucidated the side reactions including condensation, polymerization, and isomerization, and proposed a reaction network. Our findings clarify the differential activity of MClx and the impact of halide anions in DESs on MClx's activity.

Efficient Conversion of Glucose to Hydroxymethylfurfural: One-pot Brønsted Base and Acid Promoted Selective Isomerization and Dehydration.

Development of elegant, selective, and efficient strategies for the production of value-added platform chemicals from renewable feedstocks are in high demand to achieve the future needs and sustainable goals. In this context, an efficient acid-promoted synthesis of highly valuable hydroxymethylfurfural (HMF) has been demonstrated from glucose, a major constituent of lignocellulosic biomass. The major challenge in the conversion of glucose to HMF is the selective isomerization of glucose to ketose, which in the present work has been successfully addressed through the amine-mediated rearrangement of glucose to aminofructose under Amadori rearrangement. Importantly, subsequent dehydration step affords HMF and regenerates the amine employed in the first step, which could be readily recovered. In addition, scale-up and successful integration into one-pot synthesis of HMF proves the efficiency and applicability of the present transformation in large scale application. In addition, the method was also successfully extended to other monosaccharides and disaccharides to produce HMF.

The isomerization of glucose to fructose in ethanol over ZrO2 on mesoporous silica prepared through in-situ and post-impregnation methods

Fructose is a vital ketose in the production of 5-hydroxymethylfurfural platform molecules. Herein, Zr-doped hexagonal mesoporous silica was prepared over in situ co-assembly (Zr-x-HMS, x is the mole ratio of Si to Zr, x = 20, 50) and post-impregnation (Zr-Imx-HMS, x = 20, 50, 100) processes to regulate its catalytic performance against the isomerization of glucose to fructose in ethanol. The post-impregnation process did not significantly change the original pore structure and morphology of HMS, Zr-Im50-HMS with medium Zr loading possessed the most Lewis acid sites with medium strength among Zr-Imx-HMS catalysts. The in situ process changed the physical properties of HMS and enhanced the interaction of Zr sites and silica framework, facilitating the formation of Lewis acid sites with medium strength. Zr-Im50-HMS possessed the most suitable acidity for fructose production, and an optimal yield of 31.2% was achieved at 160 °C and 20 min. Moreover, the recyclability of Zr-Im50-HMS was acceptable.

Facile Synthesis of Silanol Group Rich Sn‐Beta for Highly Efficient Isomerization of Glucose to Fructose

AbstractThe isomerization of glucose to fructose is an important process in the conversion of biomass into valuable fuels and chemicals. Development of efficient catalyst for this reaction has attracted much attention. In this study, Sn‐Beta zeolites with rich silanols were synthesized for glucose isomerization by solid‐state ion‐exchange method, where Si‐Beta zeolites with different amounts of silanols were applied as the precursors. It is confirmed that open Sn sites show much higher catalytic performance than closed Sn sites for glucose isomerization (about 2.1 times). The silanol amount in Si‐Beta not only affects the formation of framework Sn sites in Sn‐Beta but also influences the isomerization reaction. More silanols in the catalyst can promote the 1,2‐H shift in isomerization and reduce the side reactions of formation of mannose and C3 products. Over 3Sn‐Beta‐3h with rich silanols, 64 % of fructose yield was obtained. Furthermore, the prepared Sn‐Beta catalyst is stable and recyclable. High fructose yield and facile synthesis method of Sn‐Beta reported in this work will contribute to the development of biomass and sugar industry.

Ball billing induced highly dispersed nano-MgO in biochar for glucose isomerization at low temperatures

The isomerization of glucose is a crucial step for biomass valorization to downstream chemicals. Herein, highly dispersed MgO doped biochar (BM-0.5@450) was prepared from rice straw via a solvent-free ball milling pretreatment and pyrolysis under nitrogen conditions. The nano-MgO doped biochar demonstrated enhanced conversion of glucose in water at low temperatures. A 31 % yield of fructose was obtained from glucose over BM-0.5@450 at 50 °C with 80.0 % selectivity. At 60 °C for 140 min, BM-0.5@450 achieved a 32.5 % yield of fructose. Compared to catalyst synthesized from conventional impregnation method (IM@450), the BM-0.5@450 catalyst shows much higher fructose yields (32.5 % vs 25.9 %), which can be attributed to smaller crystallite size of MgO (11.32 nm vs 19.58 nm) and homogenous distribution. The mechanism study shows that the activated MgOH+·OH− group by water facilitated the deprotonation process leading to the formation of key intermediate enediol.

Catalytic Dehydration of Biomass-Derived Feedstocks to Obtain 5-Hydroxymethylfurfural and Furfural

Biomass-produced furanics, furfural and 5-hydroxymethylfurfural (5-HMF), are considered as vital platform chemicals used in the production of active pharmaceutical ingredients (APIs), commodity goods, and fuels. The primary challenge associated with their production pertains to the high cost involved in scaling up to industrial levels. Consequently, it is essential to explore more cost-effective options that yield efficient end products. In this study, the use of Lewis and Brønsted acids such as HCl and AlCl3 enhances the isomerization of glucose through catalytic dehydration into 5-HMF. It was observed that employing moderate reaction conditions increased the yield of 5-HMF to 44.94 % and 50.60 % respectively, with changes in HCl concentration and AlCl3 mass loading. The suitable conditions to achieve the highest yield of 5-HMF were 100 μL of HCl, 0.75 g of AlCl3, reaction temperature 150 °C, and reaction time 4 h. In the second experiment, corncob was converted into furfural in the presence of 20 % H2SO4, in combination with NaCl as a promoter. The optimal conditions under which a yield of 44.77 % was achieved were as follows: 50 mL of 20 % H2SO4, reaction temperature 140 °C, 0.5 g of NaCl, 5 g of corncob, and reaction time 160 min. Furthermore, a proposed reaction mechanism was outlined to elucidate the pathway for the production of the aforementioned platform chemicals.

Highly selective oxidation of glucose to formic acid and exploring reaction pathways using continuous flow microreactors

The process of converting glucose into formic acid (FA) has been explored as a promising route for using biomass as a renewable feedstock for green chemical manufacturing. However, the most commonly used batch-tank reactor systems currently suffer from several drawbacks, including extended processing time, limited product selectivity, and high energy consumption, while the underlying reaction paths have been poorly understood. In this work, a continuous flow microchannel reactor was employed for the glucose conversion catalyzed by H5PV2Mo10O40 with O2 as an oxidant. The influence of various parameters on the conversion rate of glucose and the FA yield was characterized. Experimental results indicated that with a residence time of less than 3 min, the glucose was completely converted, and the highest FA yield reached 82.40 %. Extensive examination on the apparent by-products revealed that most of them acted as intermediates to produce FA through various pathways, including glyoxal, glyceraldehyde and glycolaldehyde as key intermediates for the oxidation of glucose to FA. Furthermore, the density functional theory (DFT) method was used to determine the bond energies of different C–C bond cleavage modes of substrate glucose and fructose produced by the isomerization of glucose. Experimentally, the conversion of three main intermediates and some other possible intermediates and their FA yield were measured with different residence time. It was also found that the CO2 was produced through the decarboxylation of α-hydroxy and α-carbonyl carboxylic acid compounds, while the aldehyde groups in the compounds were more likely converted to FA by the α-carbon bond cleavage. Finally, plausible reaction pathways were proposed for the process of glucose-to-FA catalyzed by HPA-2, providing useful guidance for the identification of side reaction pathways and further improvement of FA yield.

Efficient Glucose Isomerization to Fructose using Photoregenerable MgSnO3 Catalyst with Cooperative Acid-Base Sites.

The isomerization of glucose to fructose plays a crucial role in the food industry and the production of biomass-derived chemicals in biorefineries. However, the catalyst used in this reaction suffers from low selectivity and catalyst deactivation due to carbon or by-product deposition. In this study, MgSnO3 catalyst, synthesized via a facile two-step process involving hydrothermal treatment and calcination, was used for glucose isomerization to fructose. The catalyst demonstrated outstanding catalytic performance, achieving a fructose equilibrium yield of 29.8 % with a selectivity exceeding 90 % under mild conditions owing to its acid-base interaction. Notably, spent catalysts can be regenerated by photoirradiation to remove surface carbon, thereby avoiding the changes in properties and subsequent loss of activity associated with conventional calcination regeneration method. This novel approach eliminates the energy consumption and potential structural aggregation associated with traditional calcination regeneration methods. The acid-base active sites of the catalyst, along with their corresponding catalytic reaction mechanism and photoregeneration mechanism were investigated. This study presents a demonstration of the comprehensive utilization of catalytic material properties, i. e., acid-base and photocatalytic functionalities, for the development of a green and sustainable biomass thermochemical conversion system.

Glucose Isomerization to Fructose Catalyzed by MgZr Mixed Oxides in Aqueous Solution

The catalytic isomerization of glucose to fructose plays a pivotal role in the application of biomass as a feedstock for chemicals. Herein, we propose a facile solid-state-grinding strategy to construct ZrO2/MgO mixed oxides, which offered an excellent fructose yield of over 34.55% and a high selectivity of 80.52% (80 °C, 2 h). The co-mingling of amphiphilic ZrO2 with MgO improved the unfavorable moderate/strongly basic site distribution on MgO, which can prohibit the side reactions during the reaction and enhance the fructose selectivity. Based on the catalyst characterizations, MgO was deposited on the ZrO2 surface by plugging the pores, and the addition of ZrO2 lessened the quantity of strongly basic sites of MgO. Additionally, the presence of ZrO2 largely enhanced the catalyst stability in comparison with pure MgO by recycling experiments.

Diaminated Cellulose Beads as a Sustainable Support for Industrially Relevant Lipases.

Environmentally persistent polystyrene or polyacrylic beads are used as supports in enzyme large-scale bioprocesses, including conversion glucose isomerization for high-fructose corn syrup production, hydrolysis of lactose, and synthesis of active pharmaceutical ingredients. In this paper, we report the development of a novel sustainable and scalable method to produce diaminated cellulose beads (DAB) as highly efficient alternative supports for industrially relevant lipases. Regenerated cellulose beads were grafted with diaminated aliphatic hydrocarbons via periodate oxidation and reductive amination. The oxidation step indicated that aldehyde content can be easily tuned through the reaction time and concentration of reactants. Reductive amination of dialdehyde cellulose was more efficient as the length of the diaminated hydrocarbon compound increased. Morphological analysis of DAB showed that cellulose chemical grafting enabled the preservation of the bead shape and internal structure upon freeze-drying. Enzymatic degradability studies demonstrated that chemical functionalization did not undermine enzyme cellulose hydrolysis. The addition of aminated moieties on cellulose dramatically increased absorption efficiency for all industrially relevant lipases used, reaching 100% for Thermomyces lanuginosus lipase (TLL). Storage and recyclability experiments demonstrated that enzymes were retained and recyclable for at least nine cycles, although the activity gradually declined after each cycle. Medium chain triacylglycerol hydrolysis in a SpinChem reactor using TLL immobilized on 1,6 DAB exhibited higher activity compared to acrylic beads (588 vs 459 U/g) suggesting that biodegradable cellulose-based materials could be a valid and attractive alternative to plastics carriers.

Continuous isomerization of glucose to fructose using activated hydrotalcite catalyst: Effects of reaction conditions

Continuous isomerization of glucose to fructose using activated hydrotalcite catalyst: Effects of reaction conditions

Efficient isomerization of glucose to fructose over Al-loaded functional lignin biopolymer

Al-loaded functional lignin biopolymer (Alx-Lbp) catalysts were synthesized using H2O2 oxidized alkali lignin and aluminum acetate via mechanochemical modification without post-calcination treatment. The Alx-Lbp catalysts exhibited higher hydrophilicity and lower surface energy than lignin-free Al-activated carbon catalysts. Unprecedented high yields (58.5 %) of fructose from glucose were obtained over Al1-Lbp in ethanol at 140 ºC in 30 min reaction time. Al1-Lbp catalyst had Lewis acid sites (47.2 μmol/g), Brønsted acid sites (6.9 μmol/g) and a surface energy of 39.1 mN/m that facilitated glucopyranose ring-opening and gave a glucose isomerization activation energy of 65.2 kJ/mol, which was lower than values reported for Lewis acid-catalyzed systems. Active sites of Al2O3 and Al(OH)3 formed on the Al1-Lbp catalyst in ethanol promoted the formation of an enediol intermediate as confirmed with isotope experiments to achieve efficient isomerization of glucose to fructose. The Al1-Lbp catalyst demonstrated recyclability and maintained its initial activity for eight times reuse.